// SPDX-License-Identifier: MIT
pragma solidity ^0.8.23;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

/**
 * @title AereVaultRelayer
 * @notice Token allowance proxy for the AereSettlement batch DEX.
 *         Users approve THIS contract once for each token they intend to trade
 *         (typically MaxUint256). AereSettlement calls into the relayer to pull
 *         tokens during batch settlement.
 *
 *         Following CoW Protocol's GPv2VaultRelayer pattern — separates token
 *         allowances from the settlement contract so the settlement contract
 *         can be upgraded without users having to re-approve.
 */
contract AereVaultRelayer is Ownable {
    using SafeERC20 for IERC20;

    /// The single authorised caller (AereSettlement). Owner can rotate it.
    address public settlement;

    event SettlementChanged(address indexed previousSettlement, address indexed newSettlement);

    modifier onlySettlement() {
        require(msg.sender == settlement, "Relayer: caller not settlement");
        _;
    }

    function setSettlement(address _settlement) external onlyOwner {
        emit SettlementChanged(settlement, _settlement);
        settlement = _settlement;
    }

    /// Pull `amount` of `token` from `from` to `to`. Only callable by the settlement contract.
    function transferFromUser(IERC20 token, address from, address to, uint256 amount) external onlySettlement {
        token.safeTransferFrom(from, to, amount);
    }
}